Gaseous electric discharge lamp device



March 13, 1934. B L 1,951,124

GASEOUS ELECTRIC DISCHARGE LAMP DEVICE Fil ed Aug. 28, 1933 INVENTOR a fl o' BY a ' AT ORNEY Patented Mar. 13, 1934 UNITED STATES PATENT orriciz Cornelis Bol, Eindhoven, Netherlands,

assignor to General Electric Company, a corporation of New York Application August 28, 1933,

In Germany September 26,

4 Claims.

The present invention relates to gaseous electric discharge lamp devices generally and more particularly the invention relates to such devices in which a metal vapor is used as the gase- 5 ous filling or as a component of the gaseous fill- The pressure of the metal vapor in the lamp corresponds to the temperature of the container of the lamp. One method of controlling the temperature of the lamp container and therewith the metal vapor pressure therein is by regulating the radiation of heat from the container. When it is desired to have the vapor of an easily vaporizable material, such as mercury, at a high pressure in the lamp, or when it is desired to have the vapor of difficultly vaporizable material, such as sodium, at an effective pressure the radiation of heat from the container is reduced to a minimum. This can be accomplished by enclosing the lamp in a transparent heat conservator, such as a double Walled glass bell having the space between the walls evacuated or filled with a gas having low heat conducting characteristics, such as argon or nitrogen.

I have observed that the part of the container into which the electrode leads are sealed, the socalled stem part of the container, frequently cracks and leaks when the lamp is enclosed in such a heat conservator. This is caused by the high temperature at said stem part during the operation of the lamp. The object-of the present invention is to provide a lamp unit comprising a gaseous electric discharge lamp device and a heat conservator therefor of suchstructure that cracks and leaks at the stem part of the container of the lamp into which the electrode leads are sealed are avoided. Still further objects and advantages attaching to the device and to its use and operation will be apparent to those skilled in the art from the following particular description.

The invention attains its objects by locating the stem part of the container outside the space enclosed by the heat conservator of the lamp unit and ventilating said stem part to maintain the temperature of said stem below that temperature at which said stem part cracks and leaks.

In the drawing accompanying and forming part of this specification an embodiment of the invention is shown in a side elevational view and the heat conservator, the supporting means for said conservator and the housing or base for the stem part of the lamp container are shown in section.-

Referring to Fig. 1 of the drawing the new Serial No. 687,230

and novel lamp unit comprises a gaseous electric discharge lamp device having a container 1, and electrodes 2 and 3 sealed therein. Said electrode 2 is the cathode and consists of a metal filament, such as a tungsten filament, coated or impregnated with an electron emitting material and is electron emitting when heated. Said electrodes 3 are annular anodes made of sheet metal, such as iron, and are located on opposite sides of said cathode 2 at equal distances therefrom. Said electrodes 2 and 3 are supported in said container 1 by current leads 4 covered by insulating tubes 5, such as tubes of magnesium oxide. Said leads 4 and said tubes 5 pass through the disc 6 which consists of metal, such as chromium steel or of insulating material, such as mica. The rim of said disc 6 is contiguous to the inner wall of said container 1 and divides said container 1 into two parts. Said disc 6 is supported in said container 1 by the insulating tubes 5 making a frictional joint therewith and by the circular indentation 16 in the wall of said container 1. A tube 17 of small internal diameter passes through said disc to facilitate the evacuation of that part of said container 1 between the disc 6 and the stem 7 during the manufacture of the device. The greater length of said tube 17 is located in that part of said container 1 between the disc 6 and the stem 7 and is below the condensation temperature of the metal'vapor filling during the operation of the lamp device.

Said container 1 is filled with a rare gas, such as neon or argon, and a quantity of vaporizable material, such as sodium, is located in the part of said container 1 surrounding the electrodes 2 and 3. The electric discharge starts in the gas and the heat therefrom vaporizes the sodium so that the gaseous atmosphere in the device during the operation thereof is a mixture of sodium vapor and rare gas. The passage through said tube 17 is closed during the first few hours of operation of the lamp device by deposits of condensed sodium. The stem '7 is thus protected by the disc 6 from the chemical effects of the m0 metal vapor during the operation of the lamp device.

The stem '1 of said container 1 is located outside of said container 1 and said current leads 4 are sealed into said stem 7. A base 8 made of insulating material, such as porcelain, bakelite, glass, or Philite. is cemented on said container 1. Four contact pins 10 are mounted on said base 8 and said leads 4 are connected to said pins 10. Said contact pins 10 make elecno trical and frictional contact with sleeves in a .gen, at a low pressure.

socket in the well known manner and container 1 is supported thereby. A plurality of openings 11 are provided in the walls of said base 8 and adjacent the stem 7 for ventilation of said stem 7. The base 8 below the holes 11 is filled with heat insulating material 9, such as asbestos.

A heat conservator in the form of a double walled jacket 12 encloses the part said container 1 surrounding the electrodes 2 and 3. The space between the Walls of said jacket 12 is either evacuated or filled with a gas having low heat conducting characteristics, such as argon or nitro- Said jacket 12 reduces the radiation of heat from the walls of said container l to a minimum to maintain a high metal vapor pressure in said container 1. The jacket 12 is supported by a metal ring 14 cemented thereto. Said ring 14 has pins 18 which fit into slots in the holder. 15 as shown and the jacket 12 is easily removed from the holder 15 and the lamp unit. A ring 13 comprising a metal spring covered with insulation material, such as asbestos, fits into the circular recess 16 of said container 1 and presses against the inner wall of jacket 12 to close the space between said container 1 and said jacket 12.

The stem part '7 and the part of said container 1 contiguous thereto is not enclosed by said jacket 12 and said parts are not subjected-to the heat insulating efiect of said jacket 12. The part of said container 1 located between the disc 6 and the stem '7 is of considerable length so that the heating of stem 7 by the gaseous electric discharge between said electrodes 2 and 3 is reduced to a minimum. The holes 11 permit the free radiation of heat from said stem 7. I have found that by virtue of the above described structure the stem 7 is at a lower temperature during the operation of the lamp unit than that temperature which would cause it to crack and leak.

While I have shown and described and have pointed out in the annexed claims certain novel features of the invention, it will be understood that various omissions, substitutions and changes in the forms and details of the device illustrated and in its use and operation may be made by those skilled in the art without departing from the broad spirit and scope of the invention, for example, other types of thermionic electrodes can be used in place of the electrode 2 shown and described and the arrangement of the electrodes can be changed, when desired and the stem 7 can be a reentrant stem when that is desired. 7

What I claim as new and desire to secure by Letters Patent of the United States is:-

1. In combination, a gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a gaseous atmosphere therein, a stem for said container and a heat conservator for said container, said stem being out of said conservator.

2. A lamp unit comprising in combination, a gaseous, electric discharge device having a container, electrodes sealed therein, a gaseous atmosphere therein comprising a metal vapor, a stem for said container and a double walled envelope for said container whereby the radiation of heat from the container of said discharge device is reduced to a minimum, said stem being in a portion of said container which extends beyond the enclosing envelope.

3. A lamp unit comprising in combination, a gaseous electric discharge device having a container, electrodes sealed therein, a metal vapor in said container, a stem for said container and a double walled envelope for said container whereby the radiation of heat from the container of said discharge device is reduced to a minimum, said stem being in a portion of said container which extends beyond the enclosing envelope.

4. A lamp unit comprising in combination a gaseous electric discharge lamp device comprising a container, electrodes sealed therein, a vaporizable material therein, a stem for said container, a base for said container surrounding said stem, said base having ventilating means therein and a double Walled envelope for said container to reduce the radiation of heat therefrom to a minimum, said stem being in a portion of said container which extends beyond the enclosing envelope.

CORNELIS BOL. 

